1. Field of the Invention
This invention relates to a nonvolatile semiconductor memory device and a method for manufacturing the same, and more particularly to a nonvolatile semiconductor memory device with a plurality of dielectric films and a plurality of electrode films alternately stacked therein, and a method for manufacturing the same.
2. Background Art
Higher capacity and lower cost are expected of a flash memory as a nonvolatile semiconductor memory device in the future. A common method for increasing the capacity of a flash memory is to advance lithography and other processing techniques to downscale the structure, thereby increasing the level of integration of memory cells. However, downscaling in processing techniques has already been close to the limit. It is difficult to significantly increase the capacity of a flash memory simply by relying on the advancement of processing techniques as conventional.
In this context, the technique of a three-dimensional flash memory attracts new attention. This technique can increase the capacity by stacking memory cells also in a three-dimensional direction (see JP-A-2007-266143). In such a three-dimensional flash memory, the level of integration in the plane can be increased by downscaling the planar structure, and the level of integration in the stacking direction can be increased by increasing the number of stacked layers. Thus, further downscaling the planar structure is useful for higher capacity also in a three-dimensional flash memory.